Some tools for checking email-sender reputation

What I’d like is a way to associate or generate a secret key with my webmail account, and by default all of my outgoing messages are signed without any input on my part. Recipients can then whitelist my emails by the cryptographic signature, confident that said messages being spam would be impossible. DKIM gets there at the domain level, but isn’t as useful when anyone can get an account at a public mail provider (gmail, for instance).

If keys and crypto are the path to online identity (passkeys with webauthn, distributed identity systems), this seems like the logical extension of such ideas. There is some ramp up time as existing graphs proof out (you receive an email from someone you know and click “trust this identity”), but it eventually pushes untrusted messages to the margins.